SystemTool

Summary

System Tool is a variant of Win32/Winwebsec - a family of programs that claims to scan for malware and displays fake warnings of "malicious programs and viruses". They then inform the user that he or she needs to pay money to register the software to remove these non-existent threats.

Win32/Winwebsec has been distributed with many different names. The name used by the malware, the user interface and other details vary to reflect each variant's individual branding. The following details describe Win32/Winwebsec when it is distributed with the name "System Tool".

To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:

Threat behavior

System Tool is a variant of Win32/Winwebsec - a family of programs that claims to scan for malware and displays fake warnings of "malicious programs and viruses". They then inform the user that he or she needs to pay money to register the software to remove these non-existent threats.

Win32/Winwebsec has been distributed with many different names. The name used by the malware, the user interface and other details vary to reflect each variant's individual branding. The following details describe Win32/Winwebsec when it is distributed with the name "System Tool".

Installation

When distributed as "System Tool", Win32/Winwebsec creates a folder under %AppData% (for a specific user or for all users) with a randomly-generated name (for example, "%AppData%\nGfKl00902"). The fake scanner is copied to this folder, using the same name as that of the folder (for example "%AppData%\nGfKl00902\nGfKl00902.exe").

It modifies the registry to ensure that the rogue is executed at each Windows start:

It also creates the following shortcuts to the rogue on the desktop and in the Start>Programs folder:

%HOMEPATH%\Desktop\System Tool 2011.lnk

%UserProfile%\Start Menu\Programs\System Tool\System Tool 2011.lnk

Payload

Displays false/misleading malware alerts

When run, System Tool performs a fake scan of the system, and falsely claims that a number of files on the system are infected with malware. Should users request that it clean the reported infections, it advises them that they need to pay money to register the program in order for it to do so.

Some examples of the interface, fake alerts, fake scanning results, and popups displayed by "System Tool" are shown below:

Terminates processes

After installation, and upon each subsequent re-boot of the system, System Tool prevents the user from launching any application by terminating its process and displaying a message that falsely claims that the process is infected. For instance, if "notepad.exe" is launched, the malware displays the following dialog:

Win32/Winwebsec, however, avoids terminating the following processes:

aeadisrv.exe

alg.exe

audiodg.exe

csrss.exe

conhost.exe

ctfmon.exe

dwm.exe

explorer.exe

httpd.exe

iastordatamgrsvc.exe

iexplore.exe

lsass.exe

lsm.exe

mfnsvc.exe

mdnsresponder.exe

nvscpapisvr.exe

nvvsvc.exe

nvsvc.exe

pdagent.exe

searchindexer.exe

services.exe

slsvc.exe

smss.exe

snort.exe

spoolsv.exe

svchost.exe

taskhost.exe

wininit.exe

winlogon.exe

wmiprvse.exe

winroute.exe

wscntfy.exe

It also changes Desktop wallpaper to the following image (located at %temp%\<random file name>.tmp):